# CVE-2026-38755: BusyBox ash heap overflow in evalcommand function

Source: https://junglewise.ai/threats/cve-2026-38755-busybox-ash-heap-overflow-in-evalcommand-function  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-15. Updated: 2026-07-15  
License: CC BY 4.0 with a link back

CVE-2026-38755 · Severity: info · CVSS 0 · Published 2026-07-15

BusyBox is a widely used software suite that provides essential command-line tools for embedded systems and Linux devices. A flaw in its command shell component allows an attacker to crash the system or cause a service outage by providing specially crafted input that triggers an infinite loop or excessive memory usage. This could lead to a denial of service, impacting the availability of connected devices or industrial equipment.

Technologies: [Busybox](https://junglewise.ai/threats/technologies/busybox). Vendors: [Busybox](https://junglewise.ai/threats/vendors/busybox).

## Quick answers

**Is CVE-2026-38755 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-38755 being exploited in the wild.

**How severe is CVE-2026-38755?** Informational severity, with a CVSS score of 0, published 15 July 2026.

**Which products and versions are affected?** Busybox 1.38.0.

**Is there a fix for CVE-2026-38755?** A patch was published on 2026-06-16: Patch proposed on BusyBox mailing list to limit recursion depth Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-38755 attacked?** It is attacked with local access or over the network, in a software library.

**Am I affected by CVE-2026-38755?** Check whether you run Busybox at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A vulnerability exists in the ash shell component of BusyBox v1.38.0. The root cause is a lack of recursion depth limiting in the evalfun() function within shell/ash.c. An attacker can trigger this by supplying crafted input that causes recursive shell function calls, leading to stack exhaustion or a heap-related crash (reported as a heap overflow in the CVE description). A patch has been proposed to implement a MAX_ASH_FUNC_DEPTH limit of 1000 to prevent this exhaustion. The attack vector depends on how the shell processes external input; if the shell executes user-supplied scripts or commands, it can be exploited locally or remotely.

## Affected products

- BusyBox BusyBox 1.38.0

## Timeline

- 2026-06-16: patched: Patch proposed on BusyBox mailing list to limit recursion depth
- 2026-07-15: disclosed: CVE published to NVD

## References

- [https://busybox.com/](https://busybox.com/)
- [https://lists.busybox.net/pipermail/busybox/2026-June/092354.html](https://lists.busybox.net/pipermail/busybox/2026-June/092354.html)

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